\section{introduction}

We will try to conduct an empirical investigation of the performance of different planners. To conduct this investigation, we will use common problem in AI system : the logistics domain.

We introduce some complication to this domain, so to resume the problem :
\begin{itemize}
  \item Cities are divided in some locations.
  \item Package (object) can be small or big. 
  \item 3 types of transport : truck, train and airplane
  \item Truck can move from any location of a city to another in the same city in one step. They can move from any location if one city to another one in another city in 13 steps. A truck can be loaded with only a big object or a maximum of 2 small. 
  \item Train can move from a train station to another one (usually in different cities). Train have no restriction about their maximum loading.
  \item Airplane can move from an airport to another one (usually in different cities). Airplane have no restriction about their maximum loading.
\end{itemize}

